Cleanup resourceless_software_draw()

content/browser/android/in_process/synchronous_compositor_output_surface.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/android/in_process/synchronous_compositor_output_surface.h"
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
 #include "cc/output/begin_frame_args.h"
 #include "cc/output/compositor_frame.h"
@@ skipping 182 matching lines @@
   SkIRect canvas_clip;
   canvas->getClipDeviceBounds(&canvas_clip);
   gfx::Rect clip = gfx::SkIRectToRect(canvas_clip);
 
   gfx::Transform transform(gfx::Transform::kSkipInitialization);
   transform.matrix() = canvas->getTotalMatrix();  // Converts 3x3 matrix to 4x4.
 
   surface_size_ = gfx::Size(canvas->getDeviceSize().width(),
                             canvas->getDeviceSize().height());
 
-  // Resourceless software draw does not need viewport_for_tiling.
+  // Resourceless software draw does not need viewport_rect_for_tile_priority.
   gfx::Rect empty;
   InvokeComposite(transform, clip, clip, empty, gfx::Transform(), false);

[boliu, 2014/08/29 00:36:11]

wait wot? Of course you need it, used the cached version.

[hush (inactive), 2014/08/29 00:50:55]

Maybe that comment is not clear enough... That comment refers to "empty" rect
passed in for viewport_rect_for_tile_priority, because empty rect is used for
the resourceless software draw.

The cached version is used after the software draw. 
On 2014/08/29 00:36:11, boliu wrote:

[boliu, 2014/08/29 00:56:32]

It's clear and it's wrong.

The viewport/matrix for tile priority must be correct (ie match the ones used in
hardware draw) at all times. Otherwise you can get widely different tiling
priorities between software and hardware draws, causing tiles to thrash.

This refactor was only possible after we separated out draw viewport and the
tile viewport. cc used to ignore tile viewport/matrix and use the old value if
it's a software draw. Now we have the old value right here, so just pass the old
values in, so no need for cc to special case software draws.

[hush (inactive), 2014/08/29 01:29:51]

Cool. I see. Uploaded another patch for it.
On 2014/08/29 00:56:32, boliu wrote:

 
   return frame_holder_.Pass();
 }
 
 void SynchronousCompositorOutputSurface::InvokeComposite(
     const gfx::Transform& transform,
     gfx::Rect viewport,
     gfx::Rect clip,
     gfx::Rect viewport_rect_for_tile_priority,
     gfx::Transform transform_for_tile_priority,
@@ skipping 70 matching lines @@
 bool SynchronousCompositorOutputSurface::CalledOnValidThread() const {
   return BrowserThread::CurrentlyOn(BrowserThread::UI);
 }
 
 SynchronousCompositorOutputSurfaceDelegate*
 SynchronousCompositorOutputSurface::GetDelegate() {
   return SynchronousCompositorImpl::FromRoutingID(routing_id_);
 }
 
 }  // namespace content